The present invention relates to a charging/discharging circuit suitably adapted for providing a center potential or reference potential of, e.g., a bipolar monolithic linear amplifier.
In a conventional charging/discharging circuit as shown in FIG. 1, a capacitor C is coupled in parallel to one of voltage dividing resistors R1 and R2. Resistors R1 and R2 divide a power supply voltage +Vcc to provide a reference potential VR. Reference potential VR is obtained from the junction node between resistors R1 and R2. Capacitor C serves to remove ripples from reference potential VR in a steady state. For improving a ripple rejection ratio of the charging/discharging circuit, the capacitance of capacitor C and/or the resistances of resistors R1 and R2 have to be sufficiently large. Meanwhile, in order to increase the rising or falling speed of reference potential VR at the time when the power supply is switched ON or OFF, the resistances of resistors R1 and R2 must be reduced so that charging and discharging time constant for capacitor C becomes small. However, when the resistances of resistors R1 and R2 are reduced, a current flowing through them is increased, resulting in large wasteful power comsumption. Thus, the above conventional circuit fails to satisfy, at the same time, the contradictory requirements for improvement of the ripple reduction ratio, increase of the rising/falling speed of reference potential VR and a low power consumption. Only one or two requirements can be satisfied while sacrificing or spoiling others.